The field of the invention is synthetic resins from polyhydric alcohol-polycarboxylic acid reaction products. The invention is particularly related to a process for the manufacture of low pilling effect polyester fiber products.
The state of the art of the present invention may be ascertained by reference to the Kirk-Othmer "Encyclopedia of Chemical Technology", Vol. 16 (1968), pages 143-159, under the section entitled "Polyester Fibers"; U.S. Pat. No. 2,465,319 which shows the preparation of polyethylene terephthalate; U.S. Pat. No. 3,391,123 of Stedley which issued July 2, 1968 and shows the state of the art of improving the pilling effect of polyethylene terephthalate textile fibers; and "Tetrahedron" 24(5), pp. 2183-2192 (1968) as reported in Chemical Abstracts, Vol. 68, p. 77457 r which discloses the preparation of the 2,4-diphenyl-cyclobutanedimethanol-1,3 preferred for use in the present invention, the disclosures of which are incorporated herein.
The present invention is particularly concerned with a further development of the method for preparing low pilling polyester fiber products, wherein yarns, fibers or fabrics made from polyesters containing from 0.1 to 5.0 mole percent referred to the acid component of substituted cyclobutanedicarboxylic acid, are irradiated with high energy light, as disclosed in U.S. patent application Ser. No. 495,074.
Because of the great number of outstanding properties, such as high melting point, resistance to chemicals, heat, hot water and light, and further because of their mechanical properties, yarns and fibers made from polyethyleneterephthalate have become of great significance in the textile industry.
In spite of the many advantages, however, polyester fibers also suffer from drawbacks. One of these is the so-called pilling effect. It is caused by fibers being pulled out of the fabric when the latter is worn, these fibers twisting into small spheres solidly anchored in the fabric. The fabric surface thereby assumes an unpleasant appearance, and the quality of the apparel is therefore decreased.
Many attempts have been undertaken to remedy this drawback of polyesters by a number of means.
The most frequently applied prior art method consists in reducing the polyester molecular weight, in obtaining correspondingly reduced specific viscosities (hereinafter abbreviated to RSV) of about 0.35 to 0.45 dl/gm (deciliters per gram as measured at a concentration of 0.23 g. in 100 ml phenol-tetrachloroethane 60/40 at 25.degree.C), with a resulting decrease in yarn strength as disclosed in Japanese Patent No. 24,932/65. However, the melt-spinning of such a material provides serious difficulties, the melt being of very low viscosity.
Another method of preventing pilling is to prepare polyesters containing such compounds as alcohols or carboxylic acids with three or more functional groups, for instance glycerin, pentaerythrite or trimesic acid, as disclosed in German Offenlegungsschrift No. 1,928,436. Partially branched polyesters are obtained in this manner. This method suffers from the drawback that very precise dosage of the branched components is required, and this is not always feasible or carried out in industrial applications. There is the danger of reticulating the polyester, so that the entire polycondensation equipment might fail.
Already several attempts have been made to chemically change the surface of polyester fibers and also fabrics made therefrom, by treating them with water, soda, ammonium, hydrazine, amines, carboxylic acids or alcohols at elevated temperatures, as disclosed in Czech Patent No. 108,639; Dutch Patent No. 91,330; French Patent No. 1,551,050; Japanese Patent No. 7,122,174; and German Auslegeschrift No. 1,024,482. It has been found, however, that such a decay or degradation may be controlled only with serious difficulties, and that reproducibility is difficult. In many instances, it has been attempted to produce weak spots in the molecule by building in chain links with hetero-atoms, especially silicon, as disclosed in U.S. Pat. No. 3,335,211 and German Auslegeschrift No. 1,273,123, with boron, as disclosed in U.S. Pat. No. 3,391,123 and German Auslegeschrift No. 1,469,127, or with aluminum, as disclosed in German Offenlegungschrift No. 1,545,039. These attempts also lead to branching or reticulation, hydrolytic dissociation being subsequently feasible at these weak spots. Again reproducibility of results is difficult according to this method. Also, the operation must be wholly water free until the desired hydrolytic dissociation. It is generally known that the latter requirement provides considerable limitations.
As clearly shown by the above, all of the known processes suffer from a series of drawbacks.